[Resolved] Block Element Post Navigation not working

Following Leo’s video I added new post navigation block element. (https://www.youtube.com/watch?v=J-VIWJiJBDQ)
It does not work building as viedeo says or with any of the block element templates.
In all cases it shows the same. See attached images (backend and frontend)
It does not respond to any change (background color, background features image, container width, …)
I have tried disabling “In same term” option, regenerating Permalinks, deactivating other plugins. It does not work.
WP 5.7.2
GenerateBlocks 1.3.3
GenerateBlocks Pro 1.0.3
GP Premium 2.0.2
Abstract theme

Is there a way to import these block elements directly into the elements?